The present invention relates to a medical device having a highly biocompatible surface and a method for manufacturing the same.
Recently, the advance of medical science has been associated with the development of various medical devices. These medical devices are required to have sufficient medical functional capability, biocompatibility and economical efficiency. The medical functional capability means characteristics controlled by the shape and dynamic feature of a device, for example, a function of storage of blood for a blood bag, a function of dialysis or filtration of blood for a dialyzer of an artificial kidney or for a filtration membrane, a function as a blood pump for an artificial heart and a function as a lens for a contact lens.
The biocompatibility means the nature of a medical device by which the device gives no damage to biocomponents such as biotic tissue and body fluid when the medical device contacts them, namely the nature to secure safety. This is controlled by the surface properties of the medical devices, in particular thin layer from the surface having the roughness of for example 100 .ANG., which contacts biocomponents such as biotic tissue and body fluid.
Although the medical devices which have been developed have sufficient medical functional capability, they have a drawback that the application procedure in use is limited because of their insufficient biocompatibility. In particular, medical devices to be in contact with blood have an important drawback that thrombus are built up at a region in contact with blood, complements are activated and so on.
Based on such background, there have been positively promoted a research in which a suitable surface modification is performed so that biocompatibility thereof is improved with sufficient medical functional capability being ensured.
For example, there is known a method to improve biocompatibility of the device by means of a process in which radiation exposure or glow discharge treatments is carried out against a device material surface for the purpose of a graft polymerization of hydrophilic monomer such as acrylamide and ethylene glycol, whereby a surface having hydrophilic property is provided. However, this method has many drawbacks, for example, that an apparatus for the treatment is expensive and it lowers economical efficiency, that it is difficult to graft uniformly in case of a device having a hollow inner surface or a complex shape and that it is difficult to graft hydrophilic polymer per se.
As an example of an alternative method taking advantage of bioactive substance, there is developed a method for preventing a thrombus from building up by means of a control release of heparin from a medical device surface or an immobilization of urokinase onto the surface. However, these methods have drawbacks, for example, that thrombus are still built up after sustained release of heparin ceases or after urokinase is devitalized, and furthermore that the shaping method and the base material allow limited selection and concurrently increase the cost.
On the other hand, there are widely applied compounds having photosensitive group such as azido group in the field of photography, typography, adhesion, coating technology and the like. Particularly in the filed of the photoresist, various compounds having azido group are put into practical use. But no attempt has been proposed to apply this technology to biocompatible medical devices.
The present invention was made to solve the problem namely there has not been developed a medical device which has a highly biocompatible surface and at the same time has sufficient medical functional capability and economical efficiency.
An object of the present invention is to provide a medical device having sufficient biocompatibility, medical functional capability and economical efficiency and a method for manufacturing the same.